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Edward, Service Technician
Category: Mazda
Satisfied Customers: 3023
Experience:  20 + years experience on various makes and models.
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2007 Mazda 6 - 2.3 liter 4 cyl -Started car one morning

Customer Question

2007 Mazda 6 - 2.3 liter 4 cyl -Started car one morning to warm up. Wife went out there and the car was off. Would not restart. (cranks but does not start)I tried that afternoon and it ran a few seconds.Got this code: P050B "Cold Start Ignition Timing Performance-Fuel rail is getting fuel.
-Can hear fuel pump prime with key.
-Will start and run with starting fluid.
-Checked all fuses, none are blown
-WILL RUN with starting fluid (getting spark)Appears injectors are not spraying? I have not removed them to see if they physically spray.
Submitted: 1 year ago.
Category: Mazda
Expert:  Edward replied 1 year ago.
Hello, Eddie here and I will do all I can to help. You need to check for power at one wire at any fuel injector (easiest one to get to is fine) with a test light or volt meter, there are 2 wires going to each fuel injector, unplug the easiest one to get to, and just turn the key to the ON position, you should get voltage on 1 of those wires, check it between the injector harness and engine ground or negative battery terminal. If you do have power to the injectors with the key ON, then we need a noid light to see if your getting injector pulse or not.
Customer: replied 1 year ago.
Confirmed yes to power at each injector. It did try to run for just a couple seconds like it was getting fuel.
Expert:  Edward replied 1 year ago.
ok, do you have a noid light by chance? it plugs into the injector harness, and should flicker when cranking indicating injector pulse. It's either lost pressure, or injector pulse, because if it runs on starter fluid, all your lacking is fuel, That code is not going to cause it not to run. So you do have the injector rail out and it isn't spraying?
Expert:  Edward replied 1 year ago.
We either need a fuel pressure gauge, (I know you hear the pump run, but that doesn't mean it's got the pressure it needs, (55-65 psi)
Expert:  Edward replied 1 year ago.
Or a noid light at this point.
Expert:  Edward replied 1 year ago.
I believe you've probably lost pressure, unless the security system is tripped, because if you lost injector pulse but you have spark, it's probably going to be the ECM at that point, the ECM provides injector pulse.
Customer: replied 1 year ago.
I can see what O'reilly Auto parts has for rentals of noid light or pressure gauge.
Expert:  Edward replied 1 year ago.
alright, see if they got something you can borrow and let me know if that sheds any light on it. thanks.
Expert:  Edward replied 1 year ago.
Your sure it's not a security issue correct? no blinking security lights , have you tried a spare key by chance?
Customer: replied 1 year ago.
It's all factory. No aftermarket security. Tried second key.As I said, it stopped running after the car had been running for a few minutes, so I can't see how security would be tripped?
Customer: replied 1 year ago.
If you have a procedure to check the immobilizer/alarm I can look for that too.I called the auto parts store and they have noid light and fuel pressure test, so I will get both tomorrow.
Expert:  Edward replied 1 year ago.
If it had immobiliser codes, you would have gotten more than that one code I would think. Also, the security light would be blinking, instead of out with key on like it should be.
Customer: replied 1 year ago.
Confirmed flashing noid light at injectors.No way to test fuel pressure. The kit they have for rent only works with older vehicles with in-line fuel filters, rubber hose, or fuel rails with schrader valves.When I disconnect the fuel hose quick connect at the fuel rail, a small amount comes out with the key turned.
Expert:  Edward replied 1 year ago.
Alright, If you have injector pulse, check fuse 18 out under the hood, (15 amp) for the fuel pump, Check all of them while your there. If the fuse is good, and you've got pulse and spark, then I would likely pull the back seat up, check for power directly at the fuel pump when cranking. (Easiest with somebody else cranking the engine while you put your voltmeter there at the fuel pump connector) I really think you've got a bad pump, and that is because you hear it prime, I just don't think it's got enough pressure if you have injector pulse and spark. I have also looked on Ebay and one store has sold over 200 of them, so that tells me it's kind of common. Let me know if you have any further questions, but I believe your going to have to replace the pump to fix it. thank you.
Customer: replied 1 year ago.
Went to the pink-n-pull yard and found a pump to try. Was a 2011 aftermarket pump (one in the car has 170K)When I pulled the old pump in my car, there was NO gas, despite the gauge showing 1/4 tank.So, problem solved. I left the junk-yard pump install, as it is newer and the old one must have some issue with the sending unit.
Expert:  Edward replied 1 year ago.
Oh wow, so the sending unit went out, and it was empty. I really didn't think about that obvious posibillty. but. obviously fuel pressure would have been low. Let me know if you have any further questions.